1. Technical Field
The present invention relates to a recording tape cassette which accommodates, within a case, a reel on which a recording tape, such as a magnetic tape, is wound.
2. Description of the Related Art
Generally, magnetic tape cassettes having a magnetic tape as a recording tape are widely used in audio devices, or video devices which are recording/playback devices. For example, in a magnetic tape cassette which is used for business at a broadcasting station, a pair of reels are rotatably accommodated in a case which is formed by joining together an upper case and a lower case formed of a synthetic resin. A magnetic tape is wound on one reel. The distal end of the magnetic tape is attached to the other reel. By drawing the magnetic tape out from the one reel to the other reel, information is recorded on the magnetic tape, or information recorded on the magnetic tape is played back.
Each reel on which the magnetic tape is wound is structured by a lower flange, a hub fixed integrally to the upper side of the lower flange, and an upper flange mounted to the upper side of the hub. The distal end of the magnetic tape is attached to the hub, and the magnetic tape is wound onto the outer peripheral surface of the hub. The magnetic tape wound on the hub is held by the upper flange and the lower flange. Further, a plurality of concave portions (grooves), which are substantially fan-shaped as seen in plan view, are formed in the inner surface of the lower flange. These concave portions remove the air which is carried in between the magnetic tape wound around the hub and the magnetic tape (hereinafter called xe2x80x9caccompanying airxe2x80x9d), so as to improve the wound form of the magnetic tape when the magnetic tape is wound on the reel.
Further, the magnetic tape is exposed at the center of the front wall of the case so that a recording/playback head of a recording/playback device can slidingly contact the magnetic tape. When the magnetic tape cassette is not in use (is not loaded in a recording/playback device), the front wall of the case is covered by a cover. The cover is structured so as to be able to be pivoted upwardly. When the magnetic tape cassette is being used (is loaded in a recording/playback device), the cover is withdrawn to above the case, such that the magnetic tape is exposed. Moreover, a metal shaft, which is shaped as a long, thin, solid cylinder, stands upright at the inner side of the front wall of the case. A guide roller formed of synthetic resin is fit with play at this shaft, and is supported at the shaft so as to be able to rotate freely. The magnetic tape which has been drawn out from the reel is trained around this guide roller such that the conveying stability of the magnetic tape is ensured.
However, magnetic tapes have been made to be thinner as the recording capacities thereof have increased, and thinner magnetic tapes are weaker. Moreover, when the surface area of the inner surface of the lower flange which supports the magnetic tape wound on the hub is reduced due to the formation of the concave portions for removing the accompanying air, the supporting strength by which the magnetic tape is supported from the inner surface of the lower flange also decreases. As a result, the magnetic tape which is drawn out from the reel cannot be sufficiently supported. The movement of the magnetic tape up to the guide roller where the magnetic tape is first trained (guided) after being drawn out from the reel increases, and it becomes easy for the magnetic tape itself to deform.
An object of the present invention is to provide a recording tape cassette in which, even if a recording tape (such as a magnetic tape) wound on a reel is thin and deforms easily, the recording tape can be supported well up to a tape guide (such as a guide roller) at which the recording tape is first guided after being drawn out from a reel.
In order to achieve the above object, the recording tape cassette of the present invention, in which a reel is rotatably accommodated in a case, is structured so as to satisfy the following conditions. The reel has a hub around which a recording tape is wound, and a flange which is mounted to an end portion of the hub and in whose inner surface a concave portion is formed. A distance of a path of the recording tape from an inner peripheral edge portion of an outer side of the concave portion to an outer peripheral edge portion of the flange, is longer than a distance of a path of the recording tape from the outer peripheral edge portion of the flange to a tape guide at which the recording tape which is drawn out from the reel is first guided.
In accordance with this structure, the portion of the recording tape up to the tape guide which first guides the recording tape after the recording tape is drawn out from the reel, can be suitably supported at the flange of the reel. Accordingly, even if the recording tape is thin, deformation thereof can be suppressed.